I think anything you put on would soon wash/wear off. Are you sure the heads aren't just a bit dirty for setting over the winter? Let them run and cycle through a few times and see if nature doesn't cure the problem.

The first time you turn on the system in the Spring, it's a good idea to clean off all the grass and dirt that has accumulated around or in the sprinkler heads. Then manually lift up and down on them a few times to clear out any other obstruction. If they still don't want to pop up, you may have a water pressure problem.

The most common cause of head popup/popdown problems is their being installed too low. A case of Hunter PGPs has a drawing on the box showing the proper install height. And yes, the proper height will seem to be too high. In most cases, the growing lawn will continue to build up, and today's too-high head will be a too-low head in some future year.